The present invention relates to methods and apparatus for making reclosable packages having a front panel opening.
In the automated manufacture of plastic reclosable packages or bags, it is known to feed a zipper assembly comprising interlocked zipper strips (formed by extrusion) to a position adjacent and transverse to a web of thermoplastic film and then attach one strip of the zipper assembly to the web by means of heat sealing. The zipper assemblies are attached at spaced intervals along the thermoplastic sheet, one zipper assembly being attached to each section of film respectively corresponding to an individual package or bag.
In accordance with one known method of feeding zipper assemblies to an automated form, fill and seal (FFS) machine, the zipper assembly is in the form of a tape that is unwound from a spool for automated feeding. The tape comprises a continuous length of interlocked fastener strips. The continuous tape is fed to a cutting device that cuts the tape at regular lengths to form an individual zipper. Each individual zipper is then transversely applied to a web of thermoplastic bag making film by heat sealing or other suitable means. The web carries the transversely applied zippers through the remaining stages of the FFS machine. Each individual zipper is incorporated into a respective package.
In many types of reclosable packages, the zipper is installed in a mouth located at the top of a receptacle. Typically this mouth is formed by the confronting top portions of front and rear panels of the receptacle. The zippered mouth of the package is oftentimes covered by a header that must be removed to gain access to the zipper.
In other types of bags, the zipper is attached to the interior surface of the front panel at an elevation below the top of the receptacle, with access to the zipper being provided via a front panel opening. The front panel opening is made by removing a portion of the front panel along a line of weakened tear resistance. One such reclosable package is disclosed in U.S. Pat. No. 5,951,453. As seen in FIG. 3 of U.S. Pat. No. 5,951,453, one zipper strip is attached to the inside surface of the front panel of the bag body, while the other zipper strip is attached to a lower marginal portion of a flange. An upper marginal portion of the flange is joined to the bag body at an upper or top seal. In accordance with one method of manufacture disclosed in U.S. Pat. No. 5,951,453, single zippers are transversely applied to a film web, one zipper per package length. The film web then carries the zippers through various stages of an FFS or packaging machine. In accordance with another disclosed method of manufacture, shown in FIGS. 6-8 of U.S. Pat. No. 5,951,453, double zippers having a common flange are transversely applied to a film web, one double zipper per a length of film for making two packages connected at their tops.
There is a need for alternative designs of reclosable packages of the type having a front panel opening, as well as methods for automated manufacture of such reclosable packages.